The present invention relates to an alkoxylation process for the production of a polyol based on a renewable resource, the polyols produced by this process, a process for the production of molded foams produced from the polyols of the present invention and to the molded foams produced from the polyols of the present invention. The polyols of the present invention are particularly suitable for use in hot-cure molding processes.
Renewable resource polyols are gaining importance in the production of molded flexible foams. This has been driven largely by the increasing cost and limited supply of petroleum based polyols, but the “green” image of the renewable products has also become a significant factor in their increased usage. OEMs, retailers and government agencies are pushing for higher renewable resource content in the finished goods they sell or purchase to take advantage of the “green” image or to reduce the dependence on petroleum based materials.
In recent years, cold cure foams have dominated the flexible molded foam market. However, for optimum processing and foam properties, these typically require the use of low hydroxyl number polyols with high primary hydroxyl content. Because of these requirements, it has proven difficult to achieve greater than about 10% renewable resource content in cold cure molded foam without significantly diminishing processing and foam properties.
The “hot-cure” molded foam process relies on cycling the mold temperature from cold to hot and back and employs hot ovens to cure the foam that is produced. It is more energy intensive than the cold cure process and requires longer mold times. Hot molded foams typically have lower resilience and lower support factor, but their strength properties (tensile, elongation and tear), compression sets and air flow are generally better than cold molded foam. Lower density foams can be produced with acceptable compression sets; however, higher venting is required which increases extrusion scrap. Current commercial hot cure polyols are produced almost exclusively with petrochemical based raw materials, primarily ethylene oxide and propylene oxide. The ethylene oxide content of the most widely used hot-cure polyols ranges from about 8% to 15% with primary hydroxyl levels of from 40 to 60%.
Polyols with high renewable content that could be used to produce good quality hot-cure molded foams would be a welcome option for molded foam producers.